In a magnetic disk drive, a magnetic head held by an actuator mechanism above a rotating magnetic disk is located on a predetermined track, to write or read data to or from the magnetic disk. A data recording area is formed on the magnetic disk. When the operation of the magnetic disk drive is ended, the magnetic head is moved out of the recording area to a predetermined position to protect data, and is held at the predetermined position while the magnetic disk drive is not in operation.
In some cases, the actuator mechanism is moved and the magnetic head is moved into the data recording area when an external shock is given to the magnetic disk drive while the magnetic disk drive is not in operation, which might cause destruction of data. Therefore, the magnetic disk drive needs to be provided with a latching mechanism for holding the actuator mechanism at the predetermined position, even if a shock is given to the magnetic disk drive. A magnetic latching mechanism and an inertial latching mechanism are representative latching mechanisms.
A known magnetic latching mechanism attracts an iron piece attached to an end part of an actuator by a magnet embedded in a rubber member to hold the actuator in place. The magnetic latching mechanism needs to attract the actuator by a strong magnetic attraction to hold the actuator in place under shocks. In such a case, in a magnetic disk drive having a VCM having a small torque constant achieved by reducing the amount of the magnet, the VCM cannot generate a torque sufficient to separate the actuator from the magnetic latching mechanism at the start of operation. If the actuator is held by magnetic attraction of a magnitude that permits separating the actuator from the magnetic latching mechanism, the actuator cannot be held in place when a shock is given.
A known inertial latching mechanism is provided with a short lever and a long lever in combination to cope with both a clockwise external shock and a counterclockwise external shock. This known inertial latching mechanism that needs to use the short and the long lever in combination needs many parts, much assembling work and place a limit to the reduction of the cost.
An inertial latching mechanism of one-piece construction provided with a built-in crash stop is disclosed in Japanese Patent Publication No. 2002-319259 (“Patent document 1”).
In recent years, magnetic disk drives which are used as a storage device for conventional computers have become widely used in the field of domestic electric utensils including, for example, DVD recorders incorporating a magnetic disk drive. In the field of domestic electric utensils, performance requirements for magnetic disk drives are not so severe as in the field of applications to computers. Instead, it is demanded that their prices be held low.
Therefore, in designing a magnetic disk drive, it is necessary to reduce the amount of materials and the number of parts ensuring the minimum necessary functions to reduce the part cost and the assembling cost of the magnetic disk drive. For example, the access time of a magnetic disk drive for a domestic electric utensil may be longer than that of a magnetic disk drive for a computer and the amount of the magnet for the voice coil motor (VCM) for driving the actuator of the magnetic disk drive can be reduced to reduce the cost.
Reduction of the cost of the inertial latching mechanism disclosed in Patent document 1 is expected through the employment of the one-piece construction. However, the crash stop needs to be disposed as a separate single-function part to enable the crash stop to exercise the basic shock absorbing function thereof satisfactorily. The inertial latching mechanism is disposed in the same plane as the coil support of an actuator that engages with the actuator. Therefore, the inertial latching mechanism needs to be installed in a space wide enough to avoid the inertial latching mechanism overlapping the coil support. A metal insert, namely, a steel pin, is driven into the inertial latching mechanism and an attractive force generated by a leakage magnetic flux from the magnet of the VCM acts on the metal insert. Therefore the inertial latching mechanism is rotationally biased in a predetermined direction.